This disclosure relates to bit processing.
Some bit processing involves so-called bit-level permutation instructions or operations in which bits of an input ordered bit array (such as an input word) are permuted to form an output ordered bit array according to values of control bits such as so-called sieve bits.
In previously proposed systems, the sieve needs to be analysed to determine how much each data bit must be shifted by (and in which direction) and an n-bit datapath comprising the equivalent of n n-to-1 multiplexers is needed to perform the shifting. Control circuitry in a previously proposed arrangement can be complicated and can lack flexibility, in that it is dedicated to a particular permutation operation.